The specific aims are : 1) to investigate the efficacy of short-term heparin therapy in the control of ulcerative colitis (UC), in conjunction with standard medical therapy, and; 2) to better define the hypercoaguable state which accompanies flares of UC and evaluation of the hypothesis that the morphological findings and clinical symptoms of UC is propagated by a hypercoaguable state. Enrollment has progressed steadily though more slowly than we had anticpiated. Consequently we have expanded the study to include other centers who have or are currently in the process of obtaining IRB approval. To date thirty patients have been enrolled. Expanded efforts at recruitment are underway.